title: DSM-IV defined conduct disorder and oppositional defiant disorder: an investigation of shared liability in female twins.
abstract: BACKGROUND
  DSM-IV specifies a hierarchal diagnostic structure such that an oppositional defiant disorder (ODD) diagnosis is applied only if criteria are not met for conduct disorder (CD). Genetic studies of ODD and CD support a combination of shared genetic and environmental influences but largely ignore the imposed diagnostic structure.
  
  
  METHODS
  We examined whether ODD and CD share an underlying etiology while accounting for DSM-IV diagnostic specifications. Data from 1446 female twin pairs, aged 11-19 years, were fitted to two-stage models adhering to the DSM-IV diagnostic hierarchy.
  
  
  RESULTS
  The models suggested that DSM-IV ODD-CD covariation is attributed largely to shared genetic influences.
  
  
  CONCLUSIONS
  This is the first study, to our knowledge, to examine genetic and environmental overlap among these disorders while maintaining a DSM-IV hierarchical structure. The findings reflect primarily shared genetic influences and specific (i.e. uncorrelated) shared/familial environmental effects on these DSM-IV-defined behaviors. These results have implications for how best to define CD and ODD for future genetically informed analyses.
authors.affiliation: Division of Behavioral Genetics, Rhode Island Hospital and Department of Psychiatry and Human Behavior, The Warren Alpert Medical School of Brown University, Providence, RI, USA.
authors.forename: V S
authors.initials: VS
authors.lastname: Knopik
authors.affiliation: Division of Behavioral Genetics, Rhode Island Hospital and Department of Psychiatry and Human Behavior, The Warren Alpert Medical School of Brown University, Providence, RI, USA.
authors.forename: L C
authors.initials: LC
authors.lastname: Bidwell
authors.affiliation: Division of Behavioral Genetics, Rhode Island Hospital and Department of Psychiatry and Human Behavior, The Warren Alpert Medical School of Brown University, Providence, RI, USA.
authors.forename: C
authors.initials: C
authors.lastname: Flessner
authors.affiliation: Division of Behavioral Genetics, Rhode Island Hospital and Department of Psychiatry and Human Behavior, The Warren Alpert Medical School of Brown University, Providence, RI, USA.
authors.forename: N
authors.initials: N
authors.lastname: Nugent
authors.affiliation: Suffolk University, Boston, MA, USA.
authors.forename: L
authors.initials: L
authors.lastname: Swenson
authors.affiliation: Midwest Alcoholism Research Center, Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Bucholz
authors.affiliation: Midwest Alcoholism Research Center, Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: P A F
authors.initials: PA
authors.lastname: Madden
authors.affiliation: Midwest Alcoholism Research Center, Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA.
authors.forename: A C
authors.initials: AC
authors.lastname: Heath
mesh_terms: D000293:Adolescent; D000328:Adult; D019958:Attention Deficit and Disruptive Behavior Disorders / Q000209:etiology / Q000235:genetics*; D002648:Child; D019955:Conduct Disorder / Q000209:etiology / Q000235:genetics*; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004200:Diseases in Twins / Q000209:etiology / Q000235:genetics*; D005260:Female; D006801:Humans; D055815:Young Adult